UNITED STATES, [US]--Several Jewish community centers across the U.S. were targeted by bomb threats on Monday, according to the JCC Association of North America, in the fourth wave of such threats in the past two months. In total, there have been 69 threats at 54 JCCs, in 27 states and a Canadian province, the organization reports — including previous threats on Jan. 9, 18 and 31, as well as 11 threats by telephone on Monday. No bombs have been found, the organization says, and all the centers affected have "returned to regular operations." Also on Monday, a century-old Jewish cemetery in Missouri discovered apparent vandalism of dozens of headstones. President Trump had been criticized for his lack of response to previous waves of threats against Jewish community centers. At his news conference on Thursday, a reporter asked what the government was planning to do about the threats, and Trump responded as though he had personally been accused of anti-Semitism. He called the question "insulting," without addressing the bomb threats. The president's daughter Ivanka Trump, who is Jewish, also commented on the attacks, without using the words "anti-Semitism" or "Jewish." On Twitter, she wrote, "America is a nation built on the principle of religious tolerance. We must protect our houses of worship & religious centers. #JCC." View More>>